Slovak Interior Minister Robert Kalinak expressed "profound regret" to the Irish government for the oversight and the three-day delay in alerting Irish authorities. Dublin security chiefs said it was foolish for the Slovaks to hide bomb parts in the luggage of unwitting passengers under any circumstances.

Security experts said the episode illustrates the inadequacy of security screening of checked luggage — the very point the Slovak authorities had sought to test when they placed real bomb components in nine passengers' bags Saturday.

Eight were detected. But the bag containing about 3 ounces of RDX plastic explosive traveled undetected through security at Poprad-Tatry Airport in central Slovakia onto a Danube Wings aircraft.

The Dublin Airport Authority confirmed that no incoming baggage is screened in Dublin. The man didn't find out about the explosives cache until Irish police, acting on a Slovak tip, raided his apartment Tuesday.

Police said they initially were led to believe the man might be a terrorist, until Slovak authorities provided more information about their role in planting the explosive.

Irish Justice Minister Dermot Ahern said Dublin police eventually confirmed that the explosive "was concealed without his knowledge or consent … as part of an airport security exercise."

A major north Dublin intersection was shut down and neighboring apartment buildings were evacuated as a precaution while Irish army experts inspected the explosive. The man was released without charge after several hours' detention.